Theory of nematic and polar active fluid surfaces

@article{Salbreux2022TheoryON,
  title={Theory of nematic and polar active fluid surfaces},
  author={Guillaume Salbreux and Frank J{\"u}licher and Jacques Prost and Andrew Callan-Jones},
  journal={Physical Review Research},
  year={2022}
}
We derive a fully covariant theory of the hydrodynamics of nematic and polar active surfaces, subjected to internal and external forces and torques. We study the symmetries of polar and nematic surfaces and find that in addition to 5 different types of in-plane isotropic surfaces, polar and nematic surfaces can be classified into 5 polar, 2 pseudopolar, 5 nematic and 2 pseudonematic types of surfaces. We give examples of physical realisations of the different types of surfaces we have identified. We… 

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